The proposed research seeks to elucidate the contribution of local interneurones and graded synaptic interactions between neurones to the integrative processes within the central nervous system that lead to behavior. The local interneurones chosen for study are those in the segmental ganglia of the locust which are involved in the coordination of limb movements. They are chosen because they are nonspiking and because it is possible to record intracellularly from them while the animal performs normal movements. Moreover, many of the neurones can be identified both physiologically and anatomically. Therefore the integrative processes in which these local interneurones participate can be directly correlated with the behavior of the animal. A multi-disciplinary approach is proposed, that will draw evidence from physiological studies using intracellular recording, from mathematical analyses of membrane constants, from morphological studies of individually stained and characterized local interneurones and from ultrastructural studies of the synaptic structures and synaptic arrangements of known local interneurones. It is expected that this approach will provide a basic understanding of the role of local interneurons and graded synaptic transmission in one nervous system. This could provide a sound base of knowledge for a future understanding of similar neurones and similar processes that occur in the mammalian central nervous system.